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Full text of "Text Book Of Mechanical Engineering"

Appendix II.

895

steam pressure is used rather than mere impulse, resulting in a
consumption of 16 Ibs. per I. H. P. hour, while running at 4800
revs, per m.; and the absolute pressures are 115 Ibs. and i Ib.
when entering and leaving respectively. In Fig. 856 the casing A
contains five wheels B B fastened to shaft c, and five fixed discs
DD carrying the guide blades. As the steam, which is super-
heated, passes between B and D in each case, it is deflected by the
guide blades against the wheel blades, causing rotation. Entering
by pipe E, through throttle valve F, into space G, it passes between
every set of blades till it emerges at H, exhausting at j. The
pressure at G being high, there is a special thrust-bearing to pre-
vent leakage, and at K K are stuffing boxes. The governor shaft
L is driven by friction gearing, and a conical cam upon it depresses
the throttle valve at regular intervals, thus admitting steam in-
termittently. The governor therefore regulates amount of opening
by sliding the cam longitudinally on shaft L. (Seepp. 966 and 1168.)

P. 664. Zeuner  Diagram  for   Meyer  Valve.  This
construction  has  already been shewn,   where opening of main

valve is given by the usual circle, and the closing of expansion
plate by a circle of relative motion. The construction may be
proved from Fig. 857, where H c is the expansion-valve circle, GC